The present invention concerns a motor vehicle steering column anti-theft device.
More precisely, the invention concerns a motor vehicle steering column anti-theft device of the type including a casing including a rotary lock which has an angular locking position in which a legitimate key can be axially introduced (conventionally from the rear towards the front) or removed, and at least one angular utilization position in which the key cannot be extracted from the lock, said lock including a rotary projecting part forming a cam that can cooperate with a control finger carried by a bolt to control the axial movements of said bolt which can slide in said casing in an axial direction between two positions: a retracted position in which it is retracted into said casing, and a forward anti-theft position towards which it is pushed elastically and in which it projects from said casing axially via a hole in said casing and prevents a part on the steering column from rotating when said lock is in said locking position with said key extracted.
There are several known examples of this type of anti-theft device which is most commonly used to prevent theft of vehicles, notably private cars.
Numerous perfections have been made to this type of anti-theft device, notably concerning the lock, to improve the strength of the device in response to known techniques used by vehicle thieves.
Nonetheless, in known devices there still exists the possibility of a thief attempting to push the bolt itself back into the casing of the anti-theft device, thereby releasing the steering column.
The present invention proposes a new design of a steering column anti-theft device of the type previously mentioned which overcomes this drawback by avoiding any possibility of pushing the bolt into the casing when the device is in its locking position, in other words in the position in which it blocks the rotation of the steering column.
The invention is therefore a motor vehicle steering column anti-theft device of the type including a casing in which a lock is mounted rotationally between an angular locking position in which a legitimate key can be axially introduced (conventionally from the rear towards the front) or removed, and at least one angular utilization position, in which said key cannot be extracted from the lock, said lock including a rotary projecting part (34) forming a cam that can cooperate with a control finger carried by a bolt to control the axial movements of said bolt which can slide in said casing in an axial direction between two positions: a retracted position in which it is retracted into said casing, and a forward anti-theft position towards which it is pushed elastically and in which it projects from said casing axially via a hole in said casing and prevents a part on the steering column from rotating when said lock is in said locking position with said key extracted, wherein:
said bolt carries a locking finger projecting radially towards the axis (A) of said casing and penetrating a locking recess formed in a lateral face of said projecting part when said bolt is in said forward anti-theft position, to prevent or limit movement of said bolt towards said retracted position;
said locking finger is automatically pushed out of said recess during rotation of said lock from said locking position into said utilization position;
said bolt is held in said retracted position, in the presence of said key, by mobile restraining means which move to an inoperative position in which said bolt is no longer held when said key is withdrawn
According to other characteristics of the invention:
The part retaining the bolt is a pawl which is mounted pivoting on an axis perpendicular to the axis of the lock, this pawl having a surface which cooperates with the key to control its position, and a notch which can engage a restraining tab on the bolt to hold the bolt;
With the bolt in the restrained position, the notch of the pawl engages the restraining tab of radial orientation of the bolt. When the lock rotates from its utilization position to its locking position, the bolt restraining tab escapes tangentially from the notch;
The pawl with the notch is carried by the lock. In the presence of a key, this notch projects radially outwards where it can engage the restraining tab of radial orientation of the bolt;
When the pawl is in its retracted position, part of the pawl extends radially inside a keyhole formed in the lock, this part bounding the aforementioned surface of control of the movements of the pawl with which cooperates the key;
The bolt restraining tab is mounted at the rear free end of a rear part of the bolt which extends into the casing;
The locking finger can slide radially through bolt acting against a return spring which presses it permanently radially inwards in the direction of said locking recess;
The locking recess is delimited radially on the inside by a flat bottom of tangential orientation, and axially at the rear by a transversal stop surface with which the locking finger can cooperate to prevent or limit movement of the bolt towards its retracted position;
The locking recess is formed in a lateral cylindrical face of the projecting part and includes a lateral ramp which pushes said locking finger (110) out of the recess during said rotation of said lock (18) to a position in which it is in contact with a transversal cylindrical shoulder (114) on said projecting part (34) thereby retracting said bolt.
The bolt includes a rear part that is housed inside said casing and a front end that carries the locking finger.